Finding the right tests…
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Finding the right tests…
Glucose
PGBS-100 gms measures your blood sugar after a 100-gram glucose drink — the largest of the three glucose loads used at Indian labs, and the one tied to the older, more detailed gestational diabetes protocol. Rather than a single post-load reading, this dose is followed by three separate timed samples, at one, two, and three hours, so your doctor sees a full curve instead of one number. It's typically ordered only after an initial 50-gram screening test comes back raised, making it a confirmatory step rather than a first-line screen.
PGBS-100 gms refers to the post-load samples taken after a 100-gram glucose drink, reported in mg/dL. Unlike the 50-gram and 75-gram versions, this dose is paired with three separate blood draws — at one, two, and three hours after the drink — rather than a single reading, in addition to the fasting sample taken beforehand. Together, these four values form the Carpenter-Coustan glucose tolerance curve used to confirm gestational diabetes.
This higher glucose load comes from the older, two-step approach to gestational diabetes screening, still commonly used in many Indian labs. Everyone is first screened with a 50-gram, one-hour test; anyone whose result is raised is called back for this 100-gram, three-hour test to confirm the diagnosis.
Using the widely used Carpenter-Coustan criteria, values of 95 mg/dL fasting, 180 mg/dL at one hour, 155 mg/dL at two hours, and 140 mg/dL at three hours are each considered abnormal. If two or more of these four values come back above their cutoff, gestational diabetes is confirmed. A single abnormal value alone is usually not enough for a diagnosis, though your doctor may recommend closer monitoring or a repeat test.
Because this involves four separate blood draws over about three hours, you'll need to stay at the lab for the full duration, sitting quietly between draws, since movement and food can change how your blood sugar responds.
Yes. This test starts with a fasting blood draw before the glucose drink, so guidance generally calls for 8 to 14 hours without food beforehand — follow your doctor's specific instruction.
Four in total. One fasting sample is taken before the drink, then further samples follow at one, two, and three hours afterward.
Using the Carpenter-Coustan criteria, the cutoffs are 95 mg/dL fasting, 180 mg/dL at one hour, 155 mg/dL at two hours, and 140 mg/dL at three hours. Two or more abnormal values out of four confirm the diagnosis.
A single abnormal value out of four is usually not enough for a diagnosis under Carpenter-Coustan criteria. Even so, your doctor may recommend closer monitoring or a repeat test.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Plan for about three hours from your fasting draw to your final sample. You'll need to remain at the centre between each timed blood draw.
This usually happens because your doctor is following the two-step gestational diabetes protocol. In that approach, a raised 50-gram screening result is confirmed with this longer 100-gram test.